1. Field of the Invention
The invention generally relates to the field of edible, hulled grain snack products. Specifically, the invention relates to a method of processing unpopped grain kernels such as popcorn kernels, whereby the popping mechanism is suppressed so that the resultant product is a partially-popped kernel that retains the desirable flavors of a fully popped kernel but provides a denser, richer food or snack food product.
2. Background of the Invention
Cereal-based food products are a prevalent source of nutrition for humans and livestock, particularly, corn, wheat and rice-based products. The individual kernels of these and other cereal grains may be processed in a variety of ways to produce numerous foodstuffs, including many forms of snack products.
Grain kernels are generally comprised of a relatively strong outer hull, referred to as a pericarp, a starchy interior material, referred to as endosperm, and the germ, which, upon germination, is the genesis the underlying grain plant.
The hull/pericarp generally covers the exterior of the kernel. The endosperm comprises a large internal volume of the kernel and provides a source of energy for kernel germination and growth. Because the endosperm of the kernel is nutrient rich and comprises the majority of the kernel itself, food products derived from grain are primarily comprised of the endosperm material.
Popped corn is a well-know grain kernel-based snack food that is popular for both its flavor and texture. There is evidence that popcorn has been consumed by humans for over 5,400 years and it is believed that popcorn was brought to Western culture at least as early as the time of Christopher Columbus. It is estimated by the U.S. Popcorn Board that Americans consume approximately 17 billion quarts of popped popcorn each year.
Another popular snack item is flavored popcorn such as is disclosed in U.S. Pat. No. 4,640,842, “Internally Flavored Hulled Cereal Grain and Process for Preparation”, issued Feb. 3, 1987, and which is incorporated herein by reference.
Research has indicated that the “popping” mechanism associated with popcorn is the result of the cooperation of the moisture contained in the endosperm and the containment and rupture of the pericarp as is more fully discussed below.
Typically, commercially available popcorn available to consumers such as Orville Redenbacher or Jiffy Pop from ConAgra Foods, Inc., has moisture content within the endosperm of the kernel of about 13.5 to 14.5%. These kernels will further comprise a pericarp structure that is strong and lacking any damage such as fractures, fissures or weak spots.
When the kernel is exposed to a sufficiently high temperature, the moisture in the endosperm heats, boils and expands within the pericarp structure, which begins to function somewhat like a pressure-cooking vessel.
As the moisture in the endosperm continues to expand, pressure continues to increase upon and within the starchy endosperm contained within the pericarp. It is estimated that the internal pressure contained in a good quality pericarp structure can be in the range of nine atmospheres (ATMs) or about 130 PSI. When the pressure within the pericarp exceeds the capacity to retain it, the pericarp will rupture and explode. At that instant, the moisture distributed throughout the endosperm is immediately exposed to a lower atmospheric pressure and abruptly expands, turning the kernel inside out and generating a fluffy endosperm, which is what is typically referred to as popcorn.
When the pericarp of a kernel is weak or damaged, the kernel may not pop at all due to steam exiting the damaged pericarp or to the fact that the endosperm moisture is too high to allow the proper internal kernel popping conditions to exist.
An alternative result occurs when endosperm moisture content levels are greater than 14%. Under appropriate endosperm moisture conditions, the kernel will partially pop, where the endosperm only partially expands. These, or unpopped kernels are sometimes referred to as “Old Maids”.
Many popcorn consumers find the taste and texture of these partially popped kernels desirable. There is therefore a need to provide a method for making a partially popped grain kernel, such as from unpopped popcorn, that is both simple and low cost and which will produce a product that is flavorful and provides a texture that is appealing to consumers.